Member of air motor

Abstract

This invention intends to provide a long life member for air motors (rotor cylinder material, front cylinder cover material, rear cylinder cover material or the like) having more greater and uniform Vickers hardness than usual and excellent in abrasion resistance, shock resistance and thermal impact resistance. For this purpose, in this invention, a contact surface of a vane-surrounding member with vanes is heated at 450 to 580° C. in the mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and 0.01 to 99 parts by volume of hydrogen sulfide based on 100 parts by volume of nitrogen, a DC voltage at 300 to 500 V is applied relative to an anode disposed in a vacuum chamber and a nitrosulphurization layer having mean value for the Vickers hardness of 800 to 1200 with a larger difference between the mean value and the maximum value or the minimum value being 100 or less, is formed on the surface of contact with the vanes by using a bright nitrogen diffusion method.

What is claimed is:  
     
       1. A member for air motors in which the surface thereof, having a complex shape, 
       is heated at 450 to 580° C. in a mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and hydrogen sulfide,  
       a DC voltage at 300 to 500V is applied relative to an anode  
       disposed in a vacuum chamber under reduced pressure and  
       a nitrosulphurization layer having a substantially uniform thickness of about 30-300 μm is formed on the surface, with a Vickers hardness of 800-1200,  
       by using a bright nitrogen diffusion method,  
       wherein said member is at least one of a rotor, cylinder, a front cylinder cover, and a rear cylinder cover; and  
       wherein the surface is heated along a heating cycle comprising raising the temperature to about 480° C. over about one hour during which evacuation is conducted with no gas supply;  
       then maintaining said temperature of approximately 480° C. in the presence of hydrogen gas without nitrogen or hydrogen sulfide;  
       then adding nitrogen and hydrogen sulfide to provide a gas mixture of approximately 80% hydrogen, 10% nitrogen, and 10% hydrogen sulfide and applying said DC voltage; and  
       then reducing the temperature over a period of about four hours in a nitrogen atmosphere substantially free of hydrogen and hydrogen sulfide, and  
       the resultant nitrosulphurization layer has a thickness of about 0.14 mm and a surface Vickers hardness varying between 1080 and 1150.  
     
     
       2. A member for air motors in which the surface thereof, having a complex shape, 
       is heated at 450 to 580° C. in a mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and hydrogen sulfide,  
       a DC voltage at 300 to 500V is applied relative to an anode  
       disposed in a vacuum chamber under reduced pressure and  
       a nitrosulphurization layer having a substantially uniform thickness of about 30-300 μm is formed on the surface, with a Vickers hardness of 800-1200,  
       by using a bright nitrogen diffusion method,  
       wherein said member is at least one of a rotor, cylinder, a front cylinder cover, and a rear cylinder cover; and  
       wherein any difference of Vickers hardness value between the mean value and either the maximum value or the minimum value is no greater than 100;  
       wherein the nitrosulfurization layer extends to a depth of 0.09 mm.  
     
     
       3. A member for air motors in which the surface thereof, having a complex shape, 
       is heated at 450 to 580° C. in a mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and hydrogen sulfide,  
       a DC voltage at 300 to 500V is applied relative to an anode  
       disposed in a vacuum chamber under reduced pressure and  
       a nitrosulphurization layer having a substantially uniform thickness of about 30-300 μm is formed on the surface, with a Vickers hardness of 800-1200,  
       by using a bright nitrogen diffusion method,  
       wherein said member is at least one of a rotor, cylinder, a front cylinder cover, and a rear cylinder cover; and  
       wherein any difference of Vickers hardness value between the mean value and either the maximum value or the minimum value is no greater than 100;  
       wherein said Vickers hardness is 700 or more under a load of 100 gf, said hardness extending to a depth of 0.09 mm.  
     
     
       4. A member for air motors in which the surface thereof, having a complex shape, 
       is heated at 450 to 580° C. in a mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and hydrogen sulfide,  
       a DC voltage at 300 to 500V is applied relative to an anode  
       disposed in a vacuum chamber under reduced pressure and  
       a nitrosulphurization layer having a substantially uniform thickness of about 30-300 μm is formed on the surface, with a Vickers hardness of 800-1200,  
       by using a bright nitrogen diffusion method,  
       wherein said member is at least one of a rotor, cylinder, a front cylinder cover, and a rear cylinder cover; and  
       wherein any difference of Vickers hardness value between the mean value and either the maximum value or the minimum value is no greater than 100;  
       wherein the hardness of the nitrosulfurization layer continuously decreases from a maximum on said surface to a depth of 0.14 mm.  
     
     
       5. A member for air motors in which the surface thereof, having a complex shape, 
       is heated at 450 to 580° C. in a mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and hydrogen sulfide,  
       a DC voltage at 300 to 500V is applied relative to an anode  
       disposed in a vacuum chamber under reduced pressure and  
       a nitrosulphurization layer having a substantially uniform thickness of about 30-300 μm is formed on the surface, with a Vickers hardness of 800-1200,  
       by using a bright nitrogen diffusion method,  
       wherein said member is at least one of a rotor, cylinder, a front cylinder cover, and a rear cylinder cover; and  
       wherein the nitrosulfurization layer extends to a depth of 0.09 mm.  
     
     
       6. A member for air motors in which the surface thereof, having a complex shape, 
       is heated at 450 to 580° C. in a mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and hydrogen sulfide,  
       a DC voltage at 300 to 500V is applied relative to an anode  
       disposed in a vacuum chamber under reduced pressure and  
       a nitrosulphurization layer having a substantially uniform thickness of about 30-300 μm is formed on the surface, with a Vickers hardness of 800-1200,  
       by using a bright nitrogen diffusion method,  
       wherein said member is at least one of a rotor, cylinder, a front cylinder cover, and a rear cylinder cover; and  
       wherein said Vickers hardness is 700 or more under a load of 100 gf, said hardness extending to a depth of 0.09 mm.  
     
     
       7. A member for air motors in which the surface thereof, having a complex shape, 
       is heated at 450 to 580° C. in a mixed gas atmosphere comprising 50 to 95% of hydrogen, and 5-50% of nitrogen and hydrogen sulfide,  
       a DC voltage at 300 to 500V is applied relative to an anode  
       disposed in a vacuum chamber under reduced pressure and  
       a nitrosulphurization layer having a substantially uniform thickness of about 30-300 μm is formed on the surface, with a Vickers hardness of 800-1200,  
       by using a bright nitrogen diffusion method,  
       wherein said member is at least one of a rotor, cylinder, a front cylinder cover, and a rear cylinder cover; and  
       wherein the hardness of the nitrosulfurication layer continuously decreases from a maximum on said surface to a depth of 0.14 mm.